Gaseous Anesthetics

Excerpt

The history of anesthesia is a relatively recent one; if one begins with the analgesia dentist, Horace Wells, who discovered the used nitrous oxide during a dental extraction in the early 1800s. The first public showing of anesthesia occurred in October 1846, when ether was used to prevent pain during surgery at Massachusetts General Hospital. The following year, in 1847, Scottish obstetrician James Y. Simpson began using chloroform to treat childbirth pain.

In 1956, halothane came into clinical practice, but it caused fulminant hepatic necrosis, which promoted the development of new inhaled agents. Methoxyflurane came into clinical use in 1960 but was found to metabolize to nephrotoxic inorganic fluoride. Enflurane in 1972 was an improvement as it was not hepatotoxic, nor did it cause myocardial sensitivity to catecholamines like halothane. However, enflurane is also metabolized to inorganic fluoride, linked to increased seizure activity.

Today, anesthesiologists have several tools for diminishing pain, awareness, movement, and the hemodynamic derangements of stress in the surgical patient. Gaseous anesthetics, used most commonly today, are a single gas nitrous oxide and volatile fluorinated liquids (isoflurane, desflurane, sevoflurane) that are administered via specific vaporizers that transform the liquids into gases that diminish and, at higher doses, eradicate patient awareness.